Oettinger, Graf, KR and ABF heads - How much do they flow?

Kind of agree their
People are looking at OEM head and work them hard to make the very best of them

But what if you work the very best of a tuner head? (graff, oettinger, drake)
Don't go too crazy but crazy enough

What are the cams spec on your head neal ?
Did you receive my pm what do you want me to do?

 

Bump!

What happened here?

Has another thread been created?

What valve lift was used for the flows quoted?

Please!

FWIW the 5 valve designs were almost certainly tossed due to the additional space required for direct injection (hi prof!), compromised squish area, and increased emphasis on throttle response especially at low rpm

Points 1 & 2 appear obvious and well known, but has there been any discussion of the disadvantages created by the increased volume of a port with 3 intake valves compared to an equivalent 2 or, heaven help us, single valve intake port?

e.g. assuming a NA engine at part throttle and ~18" vacuum, any additional air squeezing past a slowly or rapidly opening throttle body must first restore the ~18" vacuum to ~atmospheric before said air becomes available to rush past the intake valves and into the combustion chamber

Therefore, in a single plenum induction system with distant throttle body a la VAG valver, an already soggy throttle response becomes infinitely worse

Having beaten on a Toyota 4A-GE 20v engined Corolla back in the day, I can vouch for the fact that compared to a 4A-GE 16v it was definitely soggy on tip in - - despite the advantages of direct coupled throttle bodies and decent looking intake runners

Colleagues report similar experiences when pedaling N.A. Ferrari and VAG 5 valve per pot engines, a "feel" which persists despite turbocharging

This "soggy" low end is anathema to the "feel" manufacturers demand in modern power plants with sporting rather than race pretentions[:^(]

And what of the challenges of managing spark and fuel under such circumstances, surely a nightmare demanding monstrous databases and precise mapping in order to meet ever tightening emissions specs?

So, it's back to the future with classic pentroof 16v designs, albeit tweaked into versions of the brilliant Harry Weslake heart shaped combustion chamber used in millions of BMC 2 valve heads

- - such as the Porsche designed Ford 2.5 V6 Duratec 4 valve heads fitted to the Taurus/Contour - - further modded by others such as Suzuki, Jaguar, and Lincoln in their 2.5, 2.7, and 3.0 iterations of that same engine

 

Hi there,

No other thread for this one, just slow progress as both I and my engine guy are both snowed under with projects. I'm hoping to see some light at the end of the tunnel in a month or so.

The flow figures quoted in the thread are Bare Port Flow, i.e, no valve (BPF), but the head was also tested with the valves in, and the valve in flow met the BPF at around 10mm valve lift.

I hope that helps a little and I will keep you posted with any updates as-and-when.